A molded part prepared by a mold transfer method using a die, including a surface which includes a slope, wherein a direction of a normal line of the slope is different from a die releasing direction; and a pattern which is formed on the surface and which includes grooves located on a portion of the slope so as to extend along the slope in the slanting direction of the slope. An optical element, which has an anti reflection function, including the molded part mentioned above, wherein the interval between two adjacent grooves is not greater than the wavelength of light irradiating the optical element. An optical device including a light source configured to emit light; and the optical element mentioned above which processes the light emitted by the light source.